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Posted by John Nagle on July 28, 2008, 5:11 pm
Brendan Gillatt wrote:
> pogo wrote:
>> I'm looking for the modern day equivalent of the old electromechanical
>> relays. I want to route power/signals from something like a motor
>> controller to one set of motors or another, so that I can use a single
>> controller instead of a controller for each motor. I would like for the
>> "channel" to remain set once it is selected. Preferably a single
>> "channel" would consist of two wires. Relays would actually work OK for
>> my application, but I don't want to eat up power by holding a switch
>> open or closed for a length of time, plus I want something that might
>> have, for example, one set of inputs and the ability to route that to
>> outputs a,b,c, or d.
>> So what am I looking for these days ?
>> Thanks!
>> JCDeen
>
> There is a silicon based device called a solid state relay (SSR) that
> should do the job. They go from tiny 100mA varieties up to hundreds of amps.
A solid state relay following a motor controller may not work.
DC solid state relays are polarized; they won't pass a DC voltage with
reverse polarity. So you can't use them with a reversing motor controller.
AC solid state relays usually are designed to switch as a sinusoidal
waveform at the rated frequency (usually 60Hz) goes through zero. So
they may not be happy with square-wave PWM motor drive power, and may refuse
to turn on or off on a solid DC signal.
How much current do you need to handle? If it's 100mA, there are simple
solutions. If it's 100A, it's harder.
John Nagle
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> relays. I want to route power/signals from something like a motor
> controller to one set of motors or another, so that I can use a single
> controller instead of a controller for each motor. I would like for the
> "channel" to remain set once it is selected. Preferably a single
> "channel" would consist of two wires. Relays would actually work OK for
> my application, but I don't want to eat up power by holding a switch
> open or closed for a length of time, plus I want something that might
> have, for example, one set of inputs and the ability to route that to
> outputs a,b,c, or d.
>
> So what am I looking for these days ?
>
> Thanks!
> JCDeen
>